Method of drafting textile fibers



April 25, w33. y L.. M: CQTQHTT 1,905,263

nal Filed Nov. 5, 1930 Patented pr. 25, 1933 l' UNITED STATES. PATENTOFFICE LOUIS M. COTCBETT, OF BROOKLINE, MASSACHUSETTS, ASSIGNOR TOTEXTILE PATENT & PROCESS CO. INCORPORATED, OF. BOSTON, MASSACHUSETTS, ACORPORATION 0F MASSACHUSETTS METHOD OF DRAFTING TEXTILE FIBERSApplication led November 5, 1930, Serial No. 493,680. Renewed August 18,1922.

The present invention relates to a method of drafting textile fibersfrom cotton or similar staple.

In the art of producing textile yarns from cotton or other fibers whichreoccur and overlap successively in the length of the strand, it is thecommon practice to lay suchv fibers in approximate parallelism by takingone or more strands of loosely-massed and lightly-twisted fibers andpassing such strands through a series of sets of pressure rolls, eachset having a progressively increased peripheral speed for the purpose ofdrawing out and attenuating the strand, with the result that thecomponent fibers are caused to slip one part past the other and so tolay longitudinally and with their axes in thc direction of the commonstrain.

i This draft-ing process is repeated many times in the production ofyarns from such fibers, the practice being to take a plurality vof heavystrands, combine them together for to take six card slivers, sizing each145.8'

yards to the pound, combine them, and draft them into a single strandsizing 133.3 yards to the pound; Six of such strands are next combinedtogether and drafted to form a Vstrand sizing 127.2 yards to the pound.This strand is then singlydrawn out so that it will size 546 yards tothe pound and two.

of such attenuated strands are combined and drafted to size 1640 yardsto the pound. Two of .the resultant strands are combined and drafted toform a strand sizing 5880 yards to the pound, and two of such strandsare combined inthe final process of spinning,'and are drafted to size33,600 yards to 'the pound, at which process the strand is twisted withperhaps thirty turns per inch and becomes yarn suitable for use.

be drawn out and attenuated to nearly fifty thousand times its originallength.

In the drawing Fig. 1 illustrates diagrammatically a typical arrangementof drafting rolls on a spinning frame with the setting of the rollscommonly employed for normal draft; and Fig. 2 representsdiagrammatically a suitable-apparatus for carrying out the wet spinningmethod with a separation of brake and delivery rolls greater than thelongest fiber length. v'

In any drafting operation, the drawing rolls must be carefully set intheir relay tive position andspeed, for if the brake rolls and deliveryrolls have the points of their common tangents, at lwhich the yarnv isseized and held and which is termed the nip,. .set further 'apart thanthe average length of the staple which they are drafting, the amount offiberslip and theresultant attenuation, will varywith the number offibers and their relative length in the immediate section of thestrandbeing` drafted. Such section, having left the brake rolls and iioatinguntil arrival at the delivery Arolls, will be controlled by neither set,with the result'that theiber slippage length. If the brake rolls anddelivery rolls are set closer together than the average length offiber,the staple will 4be badly broken, or' in some cases the strand will notdrw but will slip in either or both sets of ro s.

Even if the drafting rolls are set with the distance between their nipsexactly coinciding with the 'average length of staple of amount of draftto obtain the best results is limited, since even though those fiberswhich are of the average length are seized immediately their rearmostend is released by the brake rolls, and are drawn through and along thefibers still retarded by the brake rolls, there are many fibers ofgreater len h than the average, and these are bro en between the tworolls, causing lint and fiy, and there are likewise many Yfibers of lesslength than the average, and these,

being uncontrolled in their passage between the two rolls, may fall offfrom the yarn body and become lint, or they may become.

staple of fiber is shown in Figure l, which illustrates the draftingrolls'on a spinning frame in the final process of drafting which theyarn undergoes.

Many efforts have been made to overcome these inherent difficulties,particularly in the spinning process, so that the draft between therolls may 4be increased, thereby eliminatingy at least one prior processof drafting. These efforts have comprised some means of controlling thefibers mechanically in their passage between 'the rolls, usually byinterposing between the rolls light pressure rolls orl aprons, revolvingor travelling in the same direction as lthe drafting rolls and at aspeed slightly. greater than the circumferential speed of the brakerolls and less than the circumferential speed of the delivery rolls. Thebrake and delivery rolls are set further apart than the greatest lengthof the'staple, and the light pressure or control rolls oraprons tend todraw the fibers released by the brake rolls along and through the fibersstill held, and to conductand control the fibers in their passage to thedelivery rolls and to brakel the fibers against the pull of the deliveryrolls. With certain classes of fibers and strands this general methodmay be used to advantage' and the draft of the rolls increased.

The disadvantages of this method lie in the fact that'the fibers areunequally controlled, in that those fibers that are in direct contactwith the controlling means are more affected than those fibers on theinside of the yarn mass, and because of .the fact that the pressure andcontrol forces are entirely vertical and the yarn section becomesroughly elliptical under such pressure, the fibers disposed at the endsof the horizontal diameter are not under the influence of thecontrolling means at all, so

surfaces with which it comes in contact and .A

so be drawn into the yarn mass and over the surfaces of the componentfibers thereof, such Wet fibers will be caused to adhere lightly one tothe other, and because the mutual adhesion between the fibers is alongtheir length when they are lying substantially,

parallel one to the other, they resist the tendency to break down theadhesive bond and remove them from such parallel proximity. In thedrafting process, the nips of the brake rolls and the delivery rolls maybe set farther apart than the longest staple of the fibers being drawn,and the wet fibers are controlled by the adhesion to the fiber mass sothat the fibers being pulled away from the yarn mass by the deliveryrolls tend to pull with them suchibers as are Heating between the brakeand the delivery rolls while such floating fibers are retarded by theiradhesion to those held by the brake rolls. A slippingalong the adhesivebond is accordingly set up as being the line of least resistance to theforce employed, with the result that all of the fibers lare at all timesequally underthe influence of the drafting process and a vuniformlystrong and evenyarn is produced.

By utilizing such a iuid asa means of controlling the fibers beingdrafted, the

amount of draft in any of the drawing operations may be greatlyincreased, as comparatively illustrated in Figure 2, which shows thestrand being drafted in the spinning operation.- Since with this methodthe rolls are set considerably farther apart than the longest length ofstaple, such fibers are never under sufficient strain for theirbreakage, and yet, because of the adhesive action of the iiuid, theshortest lfibers are always bound to the yarn mass and controlledthereby so that lint and fly are eliminated, and such short fibers arespun into the'final yarn instead of falling offand being lost to theadvantage of the yarnboth in strength and evenness. A Very valuablecorollary to this feature is that mixed stocks of staplesare permitted,so that the cheaper short staples may be combined with the longer andmore expensiie staples without being lost in the drafting processes,producing a yarn approximately equivalent in evenness and strength toone produced entirely from long and expensive staples. It is also truethat the present troublesome and expensive practice of humidifying theroom in which the drafting operation is carried out is eliminated sincethe yarn, being wet, does not require the advantages of a moistatmosphere. For wetting the fibers prior to or during the draftingprocess, it is desirable to luti,n lize a penetrant liquid,` such asalcohol, benzine, carbon tetrachloride, or water conceivably treatedwith a reagent such as alcohol or soap for the purpose of reducing thenormal surface tension. With this method of treating, the fluid tends tospread itself evenly over the surface of the fibers with which it comesin contact, regardless of their position or disposition in the fibermass.

Referring particularly to the partially diagrammatic illustration of theinvention, the

ligure illustrates approximately the method of drafting now and commonlyin vogue. In this showing, delivery rolls indicated at 10 cooperate withbrake rolls 12 to draw out and attenuate the fibrous strand. The long,short and average k fiber lengths are indifibers, and attenuating thewet strand by passing it between successive sets of rolls or Athe like.

strand of mutually adhering wet fibers by i passing between successivesets of drawing rolls or the like, spaced apart by an amount whichexceeds approximately the greatest Vfiber length in the strand to avoidthe imposition of mechanical control throughout the region offiberslippage. l

LOUIS M. COTCHETT.

cated immediately below the delivery and A brake rolls, and from thisshowing itywill be evident that the separation between the nips of therolls approximates the average fiber length. In the proposed method ofdrawing, the usual delivery and brake rolls 10 and 12 are employed, butbefore engaging therewith the fibrous strand is passed through andcompletely immersed in a bath of penetrant 14 in a trough 16,-thestrand" being engaged and caused to pass through the liquid bv a roll18. Thereafter the 'wet strand is delivered to back rolls 20 and thenceto the brake rolls 12 and delivery rolls 10. By pre-wetting and forminga coherent strand in this manner, the separation of the rolls, asindicated, may be such as to exceed the longest staple in the mass, asindicated.l below the rolls.

What is claimed is:

' 1. The method of preparing cotton for spinning which consists inlaying individual fibers in approximate parallelism and overlappingrelationship to produce a roving or sliver strand, subjecting the strandto a bath of liquid of sufficiently low surface tension to so thoroughlywet the strand that it becomes a coherent strand of mutually adheringwet fibers, and attenuating the-wet strand by passing it betweensuccessive sets of rolls or the like.

2. The method of preparing cotton for spinning which consists in layingthe individual fibers in approximate parallelism and overlappingrelationship to produce a roving or sliver strand, subjecting the strandto a bath of liquid of substantially lower surface tension than that ofwater to so thoroughly wet the strand that it becomes a coherent strandof mutually adhering. wet

